JP5185726B2 - Vaporizer, thin film forming apparatus, and MOCVD apparatus - Google Patents

Description

  The present invention relates to a vaporizer, a thin film forming apparatus, and an MOCVD apparatus.

A problem in the development of DRAMs is memory capacitance associated with miniaturization. From the standpoint of soft errors, the capacity is required to be the same as that of the previous generation. As a countermeasure, the cell structure up to 1M is a planar structure, but a solid structure called a stack structure or a trench structure has been introduced from 4M, and the capacitor area has been increased. As the dielectric film, a film in which a thermal oxide film and a CVD nitride film are laminated on poly-Si from a thermal oxide film of the substrate Si (this laminated film is generally referred to as an ON film) is employed. In the 16M DRAM, in order to further increase the area contributing to the capacity, the stack type has adopted a thick film type that uses the side surface, a fin type that also uses the back surface of the plate, and the like.

However, in such a three-dimensional structure, an increase in the number of steps due to complicated processes and a decrease in yield due to an increase in level difference are regarded as problems, and realization after 256 Mbits is difficult. Therefore, as one way to further increase the integration without changing the structure of the current DRAM, a method of switching the capacitance dielectric to a ferroelectric having a high dielectric constant has been devised. As a dielectric thin film having a high dielectric constant, Ta ₂ O ₅ , Y ₂ O ₃ , HfO _2, etc. were first noticed as a thin film of a high dielectric constant single metal paraelectric oxide. Each dielectric constant is Ta ₂
O ₅ is 28, Y ₂ O ₃ is 16, HfO ₂ is about 24, which is 4 to 7 times that of SiO ₂ .

However, a three-dimensional capacitor structure is necessary for application after 256 MDRAM. As a material having a dielectric constant higher than these oxides and expected to be applied to DRAMs, (
_{Ba x Sr 1-x) TiO} 3, Pb (Zr y Ti 1-y) O 3, (Pb a L 1 -a) (Zr b Ti 1-b) O
_Three types of 3 are considered promising. A Bi-based layered ferroelectric material having a crystal structure very similar to that of a superconducting material is also promising. In particular, SrBi ₂ TaO ₉ called Yl material is excellent in low voltage driving and fatigue characteristics. In recent years, it has attracted much attention.

In general, the SrBi ₂ TaO ₉ ferroelectric thin film is formed by a practical and promising MOCVD (metal organic chemical vapor deposition) method.

The raw material for the ferroelectric thin film is generally three kinds of organometallic complexes Sr (DPM) ₂ and Bi (C ₆ H
₅ ) ₃ and Ta (OC ₂ H ₅ ) ₅ , each dissolved in a THF (tetrahydrofuran) solvent and used as a solution. Note that DPM is an abbreviation for dibibyromethane.

  The respective material properties are shown in Table 1.

Table 1
Boiling point (° C) / Pressure (mmHg) Melting point (° C)

Sr (DPM) ₂ 242/14 78
Bi (C ₆ H ₅ ) ₃ 270-280 / 1 201
Ta (OC ₂ H ₅ ) ₅ 146 / 0.15 22
THF 67-109

The apparatus used for the MOCVD method is a reaction part for forming a film by subjecting a SrBi ₂ TaO ₉ thin film material to gas phase reaction and surface reaction, SrBi ₂ TaO _9. It is composed of a supply section for supplying the thin film raw material and the oxidizing agent to the reaction section, and a recovery section for collecting the product in the reaction section.

  The supply unit is provided with a vaporizer for vaporizing the thin film raw material.

Conventionally, a technique shown in FIG. 12 is known as a technique related to a vaporizer. FIG. 12 (a)
What is shown in the figure is what is called a metal filter type, the gas present in the surroundings and SrBi
₂ TaO ₉ In this method, vaporization is performed by dropping a raw material solution heated to a predetermined temperature onto a metal filter used for the purpose of increasing the contact area with the ferroelectric thin film raw material solution.

However, this technique has a problem that the metal filter is clogged after several vaporizations and cannot be used for a long time.

FIG. 12B shows a technique for applying a pressure of 30 kgf / cm ² to the raw material solution to release the raw material solution from 10 μm pores and vaporize the raw material solution by expansion.

However, this technique has a problem that the pores are clogged after several uses, and cannot be used for a long time.

The raw material solution is a mixed solution of a plurality of organometallic complexes, for example, Sr (DPM) ₂ / TH
It is a mixed solution of F and Bi (C ₆ H ₅ ) ₃ / THF and Ta (OC ₂ H ₅ ) ₅ / THF. When this mixed solution is vaporized by heating, the solvent having the highest vapor pressure (in this case, THF) However, since the organometallic complex is deposited on the heating surface, a problem arises in that a stable raw material cannot be supplied to the reaction section.

Further, in MOCVD, in order to obtain a film having excellent uniformity, it is required to obtain a vaporized gas in which the raw material solution is uniformly dispersed. However, the above prior art cannot always meet such a request.

An object of the present invention is to provide a vaporizer for MOCVD that can be used for a long time without causing clogging and the like and can stably supply a raw material to a reaction section.

An object of this invention is to provide the vaporizer for MOCVD which can obtain the vaporization gas in which the raw material solution was disperse | distributed uniformly, and the vaporization method of a raw material solution.

The invention according to claim 1 is a vaporization tube that heats and vaporizes a gas containing a raw material solution;
A gas passage for supplying a gas containing the raw material solution to the vaporization pipe;
A vaporizer having
The gas passage is a carburetor formed by fitting a rod having a groove formed on a surface thereof into a cylindrical hollow portion.
The invention according to claim 2 is a vaporization tube for heating and vaporizing a gas containing a raw material solution;
A gas passage for supplying a gas containing the raw material solution to the vaporizing tube;
A vaporizer having
The gas passage is a cylindrical hollow portion having a groove on the surface, a carburetor characterized in that it is formed by fitting the rod.
The invention according to claim 3 is the vaporizer according to claim 1 or 2, further comprising a raw material supply hole communicating with the gas passage.
The invention according to claim 4 is the carburetor according to any one of claims 1 to 3, wherein the groove is formed in parallel with a longitudinal central axis of the rod.
The invention according to claim 5 is the vaporizer according to any one of claims 1 to 3, wherein a plurality of the grooves are formed.
The invention according to claim 6 is the vaporizer according to claim 5, wherein an organic solvent is supplied to one of the plurality of grooves.
A seventh aspect of the present invention is a thin film forming apparatus having a vaporizer according to any one of the first to sixth aspects.
The invention according to claim 8 is an MOCVD having the vaporizer according to any one of claims 1 to 6.
Device.

ADVANTAGE OF THE INVENTION According to this invention, the vaporizer for MOCVD which can be used for a long term without causing clogging etc. and can supply a raw material stably to a reaction part can be provided.

  According to the present invention, a vaporized gas in which an organometallic material is uniformly dispersed can be obtained.

Example 1
FIG. 1 shows a vaporizer for MOCVD according to the first embodiment.

In this example, the gas passage 2 formed inside the dispersion part main body 1 constituting the dispersion part,
A gas inlet 4 for introducing a pressurized carrier gas 3 into the gas passage 2;
Means (raw material supply hole) for supplying the raw material solution 5 to the carrier gas passing through the gas passage 2
6 and
A gas outlet 7 for sending a carrier gas containing the dispersed raw material solution 5 to the vaporization section 22;
Means (cooling water) 18 for cooling the carrier gas flowing in the gas passage 2;
A dispersion unit 8 having
A vaporization tube 20 having one end connected to the reaction tube of the MOCVD apparatus and the other end connected to the gas outlet 7 of the dispersion unit 8;
A heating means (heater) 21 for heating the vaporizing tube 20;
A vaporizing section 22 for heating and vaporizing the carrier gas in which the raw material solution is dispersed, which is sent from the dispersing section 8;
Have

  Hereinafter, this embodiment will be described in more detail.

In this example, a hole (cylindrical hollow part) having a diameter of 4.50 mm is formed in the dispersion part main body 1 and has an outer diameter larger than the inner diameter of the hole so as to be located at the center of the hole (4.48 mm). Diameter) The rod 10 is embedded. A gas passage 2 is formed by a space formed between the dispersion portion main body and the rod 10. The rod 10 is fixed by screws 9a, 9b, 9c, 9d. The width of the gas passage 2 is 0.01 mm.

In addition, as a width | variety of a gas channel, 0.005-0.10 mm is preferable. 0.005mm
If it is less than this, processing is difficult. If it exceeds 0.10 mm, it is necessary to use a high-pressure carrier gas in order to increase the carrier gas speed.

A gas inlet 4 is provided at one end of the gas passage 2. A carrier gas (for example, N ₂ , Ar) source (not shown) is connected to the gas inlet 4.

A material supply hole 6 is provided at a substantially central side portion of the dispersion main body 1 so as to communicate with the gas passage 2. The raw material solution 5 is dropped into the gas passage 2 and the raw material solution 5 passes through the gas passage 2. The raw material solution 5 can be dispersed in the carrier gas.

At one end of the gas passage 2, a gas outlet 7 communicating with the vaporization pipe 20 of the vaporization unit 22 is provided.

A space 11 for flowing the cooling water 18 is formed in the dispersion unit main body 1, and the carrier gas flowing in the gas passage 2 is cooled by flowing the cooling water 8 in this space. Alternatively, for example, a Peltier element or the like may be installed and cooled instead of this space. Since the inside of the gas passage 2 of the dispersion portion 8 is affected by the heat of the heater 21 of the vaporization portion 22, the solvent of the raw material solution and the organometallic complex are not simultaneously vaporized in the gas passage 2. End up. Therefore, by cooling the carrier gas in which the raw material solution flowing in the gas passage 2 is dispersed, vaporization of only the solvent is prevented. In particular, cooling downstream of the raw material supply holes 6 is important, and at least cooling of the downstream of the raw material supply holes 6 is performed. The cooling temperature is a temperature below the boiling point of the solvent. For example, in the case of THF, it is 67 ° C. or lower. In particular, the temperature at the gas outlet 7 is important.

In addition, by cooling the dispersion part, even if it is used for a long period of time, clogging with carbides in the gas passage (especially the gas outlet) does not occur.

The dispersion unit body 1 is connected to the vaporizing tube 20 on the downstream side of the dispersion unit body 1. The dispersion part main body 1 and the vaporization pipe 20 are connected by a joint 24, and this part becomes a connection part 23.

The vaporization unit 22 includes a vaporization tube 20 and a heating means (heater) 21. The heater 21 is a heater for heating and vaporizing the carrier gas in which the raw material solution flowing in the vaporizing tube 20 is dispersed. For example, the heater 21 may be configured by attaching a Peltier element to the outer periphery of the vaporizing tube 20.

As the vaporizing tube 20, for example, stainless steel such as SUS316L is preferably used. The dimensions of the vaporizing tube 20 may be appropriately determined. For example, the outer diameter is 3/4 inch and the length is 100.
What is necessary is just to use the thing of mm.

The downstream end of the vaporization tube 20 is connected to the reaction tube of the MOCVD apparatus. In this example, the vaporization tube 20 is used.
An oxygen supply port 25 is provided as an oxygen supply means so that oxygen heated to a predetermined temperature can be mixed into the carrier gas.

  First, the start of the raw material solution to the vaporizer will be described.

As shown in FIG. 3, the raw material supply port 6 has reserve tanks 32a, 32b, 3 respectively.
2c, 32d are mass flow controllers 30a, 30b, 30c, 30d and valve 3
They are connected via 1a, 31b, 31c, 31d.

Each reserve tank 32a, 32b, 32c, 32d is connected to a carrier gas cylinder 33.

  The details of the reserve tank are shown in FIG.

The reserve tank is filled with the raw material solution, and each reserve tank (with an internal volume of 300 cc, 3 kgf / cm ² of carrier gas is supplied to SUS. The inside of the reserve tank is pressurized by the carrier gas. The raw material solution is pushed up in the tube on the side in contact with the solution, and is a liquid mass flow controller (manufactured by STEC, full scale flow rate 0.2 cc / m
in), where the flow rate is controlled and transported to the raw material supply hole 6 from the raw material supply inlet 29 of the vaporizer.

It is transported to the reaction section by a carrier gas controlled at a constant flow rate by a mass flow controller (manufactured by STEC, full scale flow rate 2 L / min). At the same time, the mass flow controller (
Made by STEC at a full scale flow rate of 2 L / min-oxygen (oxidant) controlled at a constant flow rate is also transported to the reaction zone.

In the raw material solution, a liquid or solid organometallic complex is dissolved in THF as a solvent at room temperature. If left as it is, the organometallic complex is precipitated by evaporation of the THF solvent, and finally becomes solid. Become. Therefore, it is assumed that the inside of the pipe in contact with the undiluted solution causes the pipe to be blocked. Therefore, in order to suppress the blockage of the pipe, it is considered that the inside of the pipe and the vaporizer after the film forming operation should be washed with THF, and a washing line is provided. Cleaning
The section from the outlet side of the liquid mass flow controller to the vaporizer, and THF
It will be washed away.

The valves 31b, 31c and 31d were opened, and the carrier gas was pumped into the reserve tanks 32b, 32c and 32d. The raw material solution is pumped to a mass flow controller (full scale flow rate 0.2 cc / min manufactured by STEC), where the flow rate is controlled and the solution raw material is transported to the raw material supply hole 6 of the vaporizer.

Meanwhile, a carrier gas was introduced from the gas inlet of the vaporizer. Note that the rod 10 may pop out if too much pressure on the carrier gas side is applied, so the maximum pressure on the supply port side is 3 kgf.
/ Cm ² or less, and the maximum flow rate that can be passed at this time is approximately 1200 cc.
/ Min, and the flow velocity of the gas passage 2 reaches up to several hundreds of m / s.

When the raw material solution is dripped from the raw material supply hole 6 into the carrier gas flowing through the gas passage 2 of the vaporizer, the raw material solution is sheared by the high-speed flow of the carrier gas and becomes ultrafine particles. As a result, the raw material solution is dispersed in an ultrafine particle state in the carrier gas. The carrier gas (raw material gas) in which the raw material solution is dispersed in an ultrafine particle state is discharged to the vaporizing section 22 at a high speed.

The three kinds of raw material solutions controlled at a constant flow rate flow into the gas passage 2 from the raw material supply holes 6 through the respective raw material supply inlets 29, move through the gas passage together with the carrier gas that has become a high-speed air flow, and then vaporize. Released to the part 22. Also in the dispersion unit 8, since the raw material solution is heated by the heat from the vaporization unit 22 and the evaporation of THF is promoted, the section from the raw material supply inlet 29 to the raw material supply hole 6 and the section of the gas passage 2 are cooled by tap water. To do.

The raw material solution released from the dispersion unit 8 and dispersed in the form of fine particles in the carrier gas is the heater 2
The vaporization is promoted during transportation through the vaporization tube 20 heated to a predetermined temperature by 1 and MOCVD.
The gas is mixed by mixing oxygen heated to a predetermined temperature from the oxygen supply port 25 provided immediately before reaching the reaction tube, and flows into the reaction tube.

A vacuum pump (not shown) was connected from the exhaust port 42, impurities such as moisture in the reaction tube 44 were removed by a decompression operation for about 20 minutes, and the valve 40 downstream of the exhaust port 42 was closed.

Cooling water was passed through the vaporizer at about 400 cc / min. On the other hand, a carrier gas of 3 kgf / cm ² was flowed at 495 cc / min to sufficiently fill the reaction tube 44 with the carrier gas, and then the valve 40 was opened. The temperature at the gas outlet 7 was lower than 67 ° C.

The inside of the vaporization tube 20 was heated to 200 ° C., the section from the reaction tube 44 to the gas pack 46 and the gas pack were heated to 100 ° C., and the inside of the reaction tube 44 was heated to 300 ° C. to 600 ° C.

The inside of the reserve tank was pressurized with a carrier gas, and a predetermined liquid was flowed with a mass flow controller.

Sr (DPM) ₂ , Bi (C ₆ H ₅ ) ₃ , Ta (OC ₂ H ₅ ) ₅ and THF are each 0.04%.
The flow rate was cc / min, 0.08 cc / min, 0.08 cc / min, 0.2 cc / min.

After 20 minutes, the valve immediately before the gas pack 46 is opened and the reaction product is collected in the gas pack 46.
It was analyzed by gas chromatograph, and it was examined whether the detected product and the product in the reaction formula examined based on the reaction theory coincided. As a result, in this example, the detected product and the product in the reaction formula examined based on the reaction theory agreed well.

Moreover, the adhesion amount of the carbide | carbonized_material in the outer surface by the side of the gas outlet 7 of the dispersion part main body 1 was measured. As a result, the adhesion amount of carbide was very small.

(Comparative Example 1)
In this example, an experiment similar to that of Example 1 was performed using the apparatus shown in FIG.

In this example, the detected product and the product in the reaction formula examined based on the reaction theory were insufficient.

In addition, the result of measuring the amount of carbide adhering on the outer surface of the dispersion unit body 1 on the gas outlet 7 side is:
The amount of carbide deposited was about five times that in Example 1.

(Example 2)
FIG. 5 shows a vaporizer for MOCVD according to the second embodiment.

In Example 1, the connection part 23 was also heated by the heater 21, but in this example,
A heater was provided only on the outer periphery of the vaporizing section 22. Further, a cooling means 50 was provided on the outer periphery of the connecting portion 23 to cool the connecting portion 23.

  The other points were the same as in Example 1.

In this example, the detected product and the product in the reaction formula examined based on the reaction theory showed better agreement than in the case of Example 1.

In addition, the result of measuring the amount of carbide adhering on the outer surface of the dispersion unit body 1 on the gas outlet 7 side is:
The amount of carbide deposited was about 1/3 that of Example 1.

(Example 3)
FIG. 6 shows a vaporizer for MOCVD according to the third embodiment.

In this example, the inside of the connection part 23 forms a taper 51 whose inner diameter increases from the dispersion part 8 toward the vaporization part 22. Such a taper 51 eliminates that portion of the dead zone and prevents the stagnation of the raw material.

  The other points were the same as in Example 1.

In this example, the detected product and the product in the reaction formula examined based on the reaction theory showed better agreement than the case of Example 2.

In addition, the result of measuring the amount of carbide adhering on the outer surface of the dispersion unit body 1 on the gas outlet 7 side is:
There was almost no deposit of carbide.

Example 4
FIG. 7 shows a modified embodiment of the gas passage.

In FIG. 7A, a groove 70 is formed on the surface of the rod 10, and the outer diameter of the rod 10 is substantially the same as the inner diameter of the hole formed in the dispersion portion main body 1. Therefore, the rod 10 can be disposed in the hole without being eccentric only by fitting the rod 10 into the hole. Further, there is no need to use screws or the like. This groove 70 becomes a gas passage.

A plurality of grooves 70 may be formed in parallel with the longitudinal center axis of the rod 10, but may be formed in a spiral shape on the surface of the rod 10. In the case of a spiral shape, it is possible to obtain a raw material gas that is more uniform.

FIG. 7B shows an example in which a protrusion is provided on the rod 10. Dispersion body 1 with the largest diameter of the protrusion
The inside diameter of the hole is almost the same as the inner diameter of the hole. A space formed between the protrusion and the protrusion and the inner surface of the hole is a gas passage.

In addition, although the example shown to (a) and (b) is an example which processed the surface of the rod 10,
Needless to say, a rod having a circular cross section may be used, and a recess may be provided in the hole to provide a gas passage.

(Example 5)
Example 5 will be described with reference to FIG.

The vaporizer for MOCVD in this example is
A gas passage formed inside;
A gas inlet 4 for introducing a pressurized carrier gas 3 into the gas passage;
Means for supplying the raw material solutions 5a and 5b to the gas passage;
A gas outlet 7 for sending a carrier gas containing the raw material solutions 5a and 5b to the vaporizer 22,
A dispersion unit 8 having
A vaporization tube 2 having one end connected to the reaction tube of the MOCVD apparatus and the other end connected to the front gas outlet 7
0,
Heating means for heating the vaporization tube 20;
Have
A vaporization unit 22 for heating and vaporizing the carrier gas containing the raw material solution sent from the dispersion unit 8;
Have
The dispersion part 8 has a dispersion part body 1 having a cylindrical hollow part, and a rod 10 having an outer diameter smaller than the inner diameter of the cylindrical hollow part,
Having one or more spiral grooves 60 on the vaporizer 22 side of the outer periphery of the rod 10,
The rod 10 is inserted into the cylindrical hollow portion.

When the raw material solution 5 is supplied to the gas passage through which the high-speed carrier gas 3 flows, the raw material solution is sheared and atomized. That is, the raw material solution which is a liquid is sheared and granulated by a high-speed flow of the carrier gas. The particulate raw material solution is dispersed in a carrier gas in a particulate state. This is the same as in the first embodiment.

  In order to perform shearing and atomization optimally, the following conditions are preferable.

The supply of the raw material solution 5 is preferably performed at 0.01 to 1 cc / min, and 0.05 to 0
. It is more preferable to carry out at 5 c / min, and it is further more preferable to carry out at 0.1 to 0.3 cc / min. When a plurality of raw material solutions (including a solvent) are supplied simultaneously, the total amount is used.

The carrier gas is preferably supplied at a speed of 50 to 300 m / sec.
It is more preferable to supply at a speed of 0 to 200 m / sec.

In this example, since the spiral groove 60 is formed on the outer periphery of the rod 10 and there is a gap space between the dispersion portion main body 1 and the rod 10, the raw material in an atomized state The carrier gas containing the solution travels straight in this gap space as a straight flow, and forms a swirl flow along the spiral groove 60.

Thus, the present inventor has found that the atomized raw material solution is uniformly dispersed in the carrier gas in a state where the straight flow and the swirl flow coexist. The reason why uniform dispersion is obtained when the straight flow and the swirl flow coexist is not necessarily clear, but it is considered as follows. Due to the presence of the swirling flow, centrifugal force acts on the flow, and a secondary flow is generated. This secondary flow facilitates mixing of the raw material and the carrier gas. That is, it is considered that a secondary derivative flow is generated in a direction perpendicular to the flow due to the centrifugal effect of the swirl flow, whereby the atomized raw material solution is more uniformly dispersed in the carrier gas.

  Hereinafter, this embodiment will be described in more detail.

In this embodiment, as an example, four kinds of raw material solutions 5a, 5b, 5c, 5d (5a, 5b, 5
c is an organic metal raw material, and 5d is a solvent raw material such as THF).

In this example, in order to mix the carrier gas (hereinafter referred to as “raw material gas”) containing the raw material solution atomized into ultrafine particles, in this example, a spiral shape is formed in the downstream portion of the portion corresponding to the raw material supply hole 6 of the rod 10. The part without the groove is provided. This portion becomes the premixing unit 65. In the premixing section 65, the three kinds of organic metal source gases are mixed to some extent, and further become a complete mixed source gas in the region of the downstream spiral structure. In order to obtain a uniform mixed raw material gas, the length of the mixing portion 65 is preferably 5 to 20 mm, and more preferably 8 to 15 mm. When out of this range, a mixed source gas having a high concentration of only one of the three types of organometallic source gases may be sent to the vaporizer 22.

In this example, a parallel portion 67 and a tapered portion 58 are provided at the upstream end portion 66 of the rod 10. The rod 1 corresponding to the parallel part 67 and the taper part 58 also in the cylindrical hollow part of the dispersion part main body 1
A parallel portion having the same inner diameter as the outer diameter of the zero parallel portion 67 and a tapered portion having the same taper as the taper of the rod 10 are provided. Therefore, when the rod 10 is inserted from the left side of the drawing, the rod 10 is held in the hollow portion of the dispersion portion body 1.

In this example, unlike the case of Example 1, since the rod 10 is tapered and held, the rod 10 can be prevented from moving even if a carrier gas having a pressure higher than 3 kgf / cm ² is used. . That is, if the holding technique shown in FIG. 8 is adopted, the carrier gas can be flowed at a pressure of 3 kg / cm ² or more. As a result, higher-speed carrier gas can be supplied. That is, a high-speed carrier gas of 50 to 300 mm / s can be supplied. The same applies to the other embodiments described above if this holding technique is adopted.

As shown in FIG. 9B, grooves 67a, 67b, 67c, 67d are formed in the portion of the rod 10 corresponding to the raw material supply holes 6 as carrier gas passages. Each groove 67a,
The depth of 67b, 67c, 67 is preferably 0.005 to 0.1 mm. 0.005
If it is less than mm, it is difficult to form the groove. Moreover, 0.01-0.05 is more preferable. By setting this range, clogging and the like are eliminated. Moreover, a high-speed flow is easy to be obtained.

Regarding the holding of the rod 10 and the formation of the gas passage, the configuration shown in FIG.

The spiral groove 60 may be one as shown in FIG. 9A, or may be a plurality as shown in FIG. Further, when a plurality of spiral grooves are formed, they may be crossed. In the case of crossing, a more uniformly dispersed source gas can be obtained.

The dimensions and shape of the spiral groove 60 are not particularly limited, and the dimensions and shape shown in FIG. 9C are given as an example.

  In this example, the gas passage is cooled by cooling water 18 as shown in FIG.

Further, in this example, the expansion unit 69 is provided independently before the entrance of the dispersion unit 22.
The expansion portion 69 is a portion for preventing the retention of the source gas described in the third embodiment. Of course, it is not necessary to provide the extended portion 69 independently, and an integrated configuration may be employed as shown in FIG.

The expansion angle θ in the expansion part 69 is preferably 5 to 10 degrees. When θ is within this range, the raw material gas can be supplied to the dispersion section without breaking the swirling flow.
Also, when θ is within this range, the fluid resistance due to expansion is minimized, the presence of dead is minimized, and the presence of eddy currents due to the presence of dead zones can be minimized. Θ
Is more preferably 6 to 7 degrees. In the case of the embodiment shown in FIG. 6, the preferable range of θ is the same.

(Example 6)
Using the apparatus shown in FIG. 8, the raw material solution and the carrier gas were supplied under the following conditions, and the uniformity in the raw material gas was examined.

Raw material solution dripping amount: Sr (DPM) ₂ 0.04 cc / min
Bi (C ₆ H ₅ ) ₃ 0.08cc / min
Ta (OC ₂ H ₅ ) ₅ 0.08 cc / min
THF 0.2cc / min
Carrier gas: Nitrogen gas
10-350m / s

An apparatus shown in FIG. 8 was used as the vaporizer. However, as the rod, a rod in which no spiral groove was formed in the rod shown in FIG. 9 was used.

The raw material solution was supplied from the raw material supply hole 6 and the speed of the carrier gas was varied. From the raw material supply hole, the groove 67a has Sr (DPM) ₂ and the groove 67b has Bi (C ₆ H
₅ ) ₃ and the groove 67c were supplied with Ta (OC ₂ H ₅ ) ₅ and the groove 67d with THF.

The source gas was sampled at the gas outlet 7 without heating in the vaporization section, and the particle diameter of the source solution in the sampled source gas was measured.

The result is shown in FIG. 11 as a relative value (1 when the apparatus according to the conventional example shown in FIG. 12A is used). As can be seen from FIG. 11, the dispersed particle size is reduced by setting the flow rate to 50 m / s or more, and the dispersed particle size is further reduced by setting it to 100 m / s or more. However, the dispersed particle diameter is saturated even when the speed is 200 m / s or more. Therefore, 100-200m
/ S is a more preferable range.

(Example 7)
In this example, a rod formed with a spiral groove was used as the rod.

  The other points were the same as in Example 6.

In Example 6, the concentration of the raw material solution supplied to the groove was high in the extended part of the groove. That is, that is, Sr (DPM) ₂ at the extension of the groove 67a, and B at the extension of the groove 67b.
Other concentrations of i (C ₆ H ₅ ) _{3 and} Ta (OC ₂ H ₅ ) ₅ were higher in the extension of the groove 67c.

However, in this example, the mixed metal gas obtained at the end of the spiral groove was uniform in each organometallic raw material in any part.

2 is a cross-sectional view showing a main part of a vaporizer for MOCVD according to Example 1. FIG. 1 is an overall cross-sectional view of a vaporizer for MOCVD according to Example 1. FIG. It is a system diagram of MOCVD. It is a front view of a reserve tank. 6 is a cross-sectional view showing a main part of a vaporizer for MOCVD according to Example 2. FIG. 6 is a cross-sectional view showing a main part of a vaporizer for MOCVD according to Example 3. FIG. (A), (b) is sectional drawing which concerns on Example 4 and shows the modification of the gas channel | path of the vaporizer for MOCVD. 6 is a cross-sectional view showing a vaporizer for MOCVD according to Example 5. FIG. The rod used for the vaporizer for MOCVD which concerns on Example 5 is shown, (a) is a side view, (b) is XX sectional drawing, (c) is YY sectional drawing. It is a side view which shows the modification of Fig.9 (a). 10 is a graph showing experimental results in Example 6. (A), (b) is sectional drawing which shows the conventional vaporizer for MOCVD.

Explanation of symbols

1 Dispersing unit body,
2 gas passage,
3 Carrier gas,
4 Gas inlet,
5 Raw material solution,
6 Raw material supply hole,
7 Gas outlet,
8 Dispersion part,
9a, 9b, 9c, 9d screws,
10 rods,
18 Means for cooling (cooling water),
20 vaporizer tubes,
21 Heating means (heater),
22 Vaporization part,
23 connections,
24 joints,
25 oxygen introduction means (oxygen supply port),
29 Raw material supply inlet,
30a, 30b, 30c, 30d Mass flow controller,
31a, 31b, 31c, 31d valves,
32a, 32b, 32c, 32d reserve tank,
33 Carrier gas cylinder,
42 exhaust port,
40 valves,
44 reaction tubes,
46 Gas pack,
51 taper,
70 groove.

Claims (8)

A vaporizing tube that heats and vaporizes the gas containing the raw material solution;
A gas passage for supplying a gas containing the raw material solution to the vaporization pipe;
A vaporizer having
The gas passage is formed by fitting a rod having a groove formed on a surface thereof into a hollow cylindrical portion. A vaporizing tube that heats and vaporizes the gas containing the raw material solution;
A gas passage for supplying a gas containing the raw material solution to the vaporizing tube;
A vaporizer having
The gas passage is formed by fitting a rod into a cylindrical hollow portion having a groove on the surface. The vaporizer according to claim 1, further comprising a raw material supply hole communicating with the gas passage. The vaporizer according to any one of claims 1 to 3, wherein the groove is formed in parallel with a longitudinal central axis of the rod. The vaporizer according to claim 1, wherein a plurality of the grooves are formed. The vaporizer according to claim 5, wherein an organic solvent is supplied to one of the plurality of grooves. A thin film forming apparatus having the vaporizer according to any one of claims 1 to 6. An MOCVD apparatus comprising the vaporizer according to any one of claims 1 to 6.

Images